Advancements in computer-aided design technology have led to systems that enable engineers to run simulations that test the physical properties of parts or systems. The ability to run simulations of the physical properties of the parts or systems prior to their the actual manufacture or implementation enables the engineer to identify potential design flaws or deficiencies during the design process. Simulations can be run, for example, to determine when and where a mechanical part will fail under load conditions, thereby enabling the engineer to strengthen or modify the part during the design process to improve its performance.
In addition to the analysis of completed parts, simulations of physical processes are also useful to identify potential problems in the manufacturing process. Injection molding, for example, is a physical process that would benefit by the application of computer simulation technology. The injection molding process consists of three stages; filling a mold with plastic under high pressure; holding and compressing the plastic into the mold; and solidifying the plastic in the mold. The process is particularly useful for manufacturing thin walled structures with complicated shapes. Many problems, however, can occur during the molding process such as a premature solidification of plastic in a part of the mold which blocks the flow of plastic into adjacent regions.
A detailed understanding of physical flow of the plastic through the mold is an essential element in mold design to avoid such problems. Traditionally, the mold designer had to design parts without the benefit of having data that simulated the dynamics involved in the molding process. Thus, the mold designer was required to rely on time consuming physical tests of a series of prototype molds to determine if parts manufactured by the molds were of sufficient quality. Adjustments to the mold design were made based on the results obtained from the prototype molds on a trial and error basis and mold design tended to be more of an art than science.
More recently, computer simulations of the molding process have been devised over the past fifteen years that enable the mold designer to simulate the flow of plastic through the mold during the design process. Cornell University of Ithaca, N.Y., for example, has maintained an ongoing research project in cooperation with the National Science Foundation, designated the Injection Molding Project, directed to computer-aided design of injection molds. The progress and results of the Injection Molding Project have been published in a series of progress reports. See generally, Injection Molding Project, Progress Reports Nos. 1-14, Wang et al., Cornell University, 1975-1988, the contents of which are herein incorporated by reference, and in particular Progress Report 11 entitled "Computer-Aided Design and Fabrication of Molds and Computer Control of Injection Molding", Wang et al., April 1985, NSF Grant MEA-8200743, Progress Report 12 entitled "Integration of CAD/CAM for Injection-Molded Plastic Parts:, by Wang et al., May 1986, NSF Grant DMC-8507371, and Progress Report 13 entitled "Integration of CAD/CAM for Injection-Molded Parts", by Wang et al., June 1987, NSF Grant DMC-8507371.
The results of the research project has yielded a computer aided engineering package referred to as the Cornell Injection Molding Program (CIMP) that enables the mold designer to simulate flow characteristics of the plastic through a mold design. Further development work based on the research done at Cornell has also produced commercially available software packages such as C-FLOW, an extension of the CIMP developed by Advanced CAE Technology, (See generally, Applications of Computer Aided Engineering in Injection Molding, ed. Louis T. Manzione, Hanser Publications, New York:Macmillian, 1987, the contents of which are herein incorporated by reference, and specifically Chapter 7 entitled "C-Flow: a CAE Package with High-Level Interface Graphics", by Wang et al.). With the aid of computer simulations, the mold designer is able to make modifications to the mold design during the design process without having to produce prototype molds, thereby significantly reducing the time required to finalize the mold design and produce production molds.
While computer packages have been developed that permit the mold designer to generate simulation data as noted above, the simulation data generated by such packages often contains large data sets having many parameters, i.e., multi-variable data, which is difficult to present in a format that can be readily interpreted by the mold designer. Conventional methods for presenting multi-variable data include the use of contour plots and three-dimensional surface elevation maps, for example a geological survey map, which plot elevation and surface type over a two-dimensional surface by the use of color and contour lines. Another approach is to use symbols, called glyphs, which represent data at sample points. See, Glyphs Getting the Picture, W. Sacco et al., Janson Publications, Inc., Providence, R.I., 1987.
The application of glyphs to present injection mold simulation data is discussed in detail in an article entitled "Visualization of Injection Molding", by R. Ellson and D. Cox, Simulation, Vol. 51, No. 5, November, 1988, incorporated herein by reference. A multi-layer glyph is used to represent the simulation data at various points in the mold during the molding process. The shape of the glyph is modified to reflect changes in the flow rate of the plastic. The temperature of the plastic is represented by the coloring of various layers of the glyph. The pressure of the plastic is represented by the coloring of a base plane of the glyph. The simulation data is processed to generate a plurality of image frames illustrating, through the use of the glyphs, the flow of the plastic through the mold. Once all of the frames are generated, a moving animation of the plastic flow can be generated by displaying the plurality of image frames in sequence.
The presentation of simulation data in the forms of glyphs as described above represents a vast improvement over conventional two-dimensional graphical presentation methods. Unfortunately, the mold designer is not able to view the animation of the plastic flow in real-time as a significant amount of processing capacity and time is required to generate pictorial representations, i.e., image frames, of the multi-variable data in easily comprehensible forms such as glyphs. For example, the system described by Ellson and Cox cited above requires about eight minutes to generate the image data for a single frame using a mini-supercomputer. A typical animation may includes one hundred animation frames. Accordingly, the generation of the image data for the animation frames alone takes between 13 and 14 hours. Additional time is required to generate a moving animation by linking the frames together. Thus, the mold designer must run the simulation program and wait several days before a moving animation of the physical phenomena can be viewed.
The primary drawbacks to achieving real-time animation are found in the basic approach taken by conventional systems to generate and display the simulation data. Conventional injection mold simulation programs as mentioned above, for example, divide the mold into a number of geometric elements represented by floating point data and characterize the flow of plastic through the geometric elements with variables, such as velocity, temperature, pressure, etc., that are also represented as floating point data. Animation processes of the type described above have centered on the generation of a list of polygons, based on the geometrical and variable floating point data, that are used to create an image frame of the physical process for each step in time.
Each image frame generated by the animation process may contain over a hundred thousand polygons. The polygons are represented by a number of vertices (3 or 4) having three-dimensional coordinates that relate to the location of the polygon within the mold cavity. The shear volume and complexity of processing the floating-point data used to generate the tens of thousands of polygons required to construct each image frame in real-time is beyond the capability conventional computer processing equipment, such as stand alone engineering workstations, that are available to the average mold designer.
Real-time animation is technically possible, of course, if large dedicated supercomputers were used to perform the processing of the floating-point data in the above-described manner. The average mold designer, however, does not have access to such computing power. Thus, even after the generation of the simulation data is complete, the mold designer must wait a significant period of time to view the simulation data in a comprehensible form.
In view of the above, it is an object of the invention to provide a method and apparatus for performing real-time computer animation that would enable the mold designer to view the animation of the simulation data in real-time, thereby enabling the mold designer to analyze the simulation data and make required corrections to modify the mold design in an efficient manner.
It is a further object of the invention to provide a method and apparatus for performing real-time computer animation that is economical and therefore readily available to the average designer.
It is an additional object of the invention to provide a method and apparatus for performing real-time computer animation of a physical phenomena that permits a user to modify the animation display.